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Physiology Quiz -Skeletal Muscle Physiology - Part 2

Skeletal muscle cells are characterized by their striated appearance when visualized under the light and electron microscopes. Collectively, skeletal muscle cells make up approximately 50% of the body’s wet (i.e., soft tissue) weight. Skeletal muscle cells perform highly important functions including generating force, motion, and even heat. Test your basic knowledge of skeletal muscle physiology by taking this simple quiz.

(1) The optimal resting length of a skeletal muscle sarcomere allows it to generate the maximum amount of force when the muscle is stimulated to contract. What is the optimal resting length of a typical skeletal muscle cell sarcomere?

(A) 2.15 pm

(B) 2.15 nm

(C) 2.15 μm

(D) 2.15 mm

(E) 2.15 m

(2) At rest, the cytoplasmic Ca2+ concentration in a typical skeletal muscle cell is about 70 nM. At the peak of the skeletal muscle cell contraction phase, the cytoplasmic Ca2+ concentration is approximately:

(A) 10−1 M

(B) 10−3 M

(C) 10−6 M

(D) 10−9 M

(E) 10−12 M

(3) In skeletal muscle cells, what percentage of cytoplasmic Ca2+ required for contraction is supplied by the sarcoplasmic reticulum?

(A) 0%

(B) 10%

(C) 20%

(D) 80%

(E) 100%

(4) Which of the following is/are required for physiologically useful skeletal muscle contractions?

(A) Tetanic contractions

(B) Recruitment of motor units

(5) In skeletal muscle cells, the dihydropyridine (DHP) receptors of the t-tubules communicate with the ryanodine receptors of the sarcoplasmic reticulum via: